Atomic Number and Mass Number

Q.

What Is The Difference Between Mole And Molecule?

Q.

How much is the gram atomic mass of oxygen?

Q. How many grams of oxygen gas contains the same number of molecules as 16g of sulphur dioxide gas. (Oxygen-16u, Sulphur-32)

Q.

The atomic number of an atom is 19 and its mass number is 39. Which of the following are correct?

1. Number of electrons = 20

2. Number of neutrons = 19

3. Number of neutrons = 20

4. Number of protons = 19

Q.

The atomic number of chlorine is 17. The total number of electrons in chlorine atom is ___.

1. 17

2. 3

3. 20

4. 13

Q. Question 26
In the atom of an element X, 6 electrons are present in the outermost shell. If it acquires noble gas configuration by accepting the requisite number of electrons, then what would be the charge on the ion so formed?

Q.

What is the mass of 1 mole of water ?

Q.

What is the molecular mass of ${\mathrm{H}}_2{\mathrm{SO}}_4$?

Q.

If an element has $15$ protons and $16$ neutrons in the nucleus, find out its atomic number and mass number. Represent the element with atomic and mass numbers.

Q.

An element may be represented as ${}_{18}{X}^{40}$ . Find the number of electrons, protons and neutrons in this atom.

Q.

Define “ Atomic number”.

Q. How many moles of oxygen atoms are there in 1.2×10²² sulphur dioxide molecules?

Q.

The atom of an element has 20 protons, 20 electrons and 20 neutrons:

Name the element.

Q.

Arrange the following in Increasing order of mass:

1. One Atom of Silver
2. One mole atoms of $\mathrm{N}$
3. $2\mathrm{g}$ of Sodium
4. $6.022\times {10}^{22}$ Atoms of Calcium

Q.

Explain with examples

Atomic number

Q. Draw orbit structure diagram of
(a) Sodium chloride (NaCl). [Atomic number Na = 11, Cl = 17].

Q.

Silicon atomic number 14 and phosphorus atomic number 15 belong to the same period of the periodic table. Write down the electronic configuration of silicon and phosphorus and name the period in which these elements occur.

Q.

An atom has a mass number of $23$ and the atomic number is $11$. The atom has ______ electrons.

Q. Hydrogen exists in three isotopic forms, ${{}^{}}_1{H}^1$, ${}_1{H^2}^{}$ , ${}_1{H}^3$ known as protium, deuterium, and tritium. Why are all the isotopes neutral in nature?

Q.

Calculate the number of moles in 12.046 *10 raised to 23 number of helium atoms

Q. The atomic number of an atom is 30 and its mass number is 60. Which of the following is correct?

1. Number of protons = 39
2. Number of neutrons = 19
3. Number of electrons = 30
4. Number of neutrons = 29

Q. Two elements A and B contain 13 and 8 proton respectively. If the number of neutrons in them happen to be 14 and 8 respectively, the formula unit mass for the compound between A and B unit would b

Q.

In the formula $CaB{r}_2$​ what does Ca stand for and what is its valency?

1. Calcium +1

2. calcium -1

3. Calcium +2

4. Calcium -2

Q. Define mass number. What is the mass number of an atom having 6 electrons and 7 neutrons?

Q.

Calculate the mass of $3.011\mathrm{x}{10}^{24}$ atoms of carbon.

Q. Which of the following statements are correct about a neutral atom?

1. Atomic number = Number of protons = Number of electrons
2. Mass number = Number of protons + Number of neutrons
3. Atomic number = Number of protons + Number of electrons
4. Mass number = Number of neutrons = Number of electrons

Q.

Which is the correct statement about $\alpha$-particle?

1. Proton is ionized hydrogen atom

2. Proton is α-particle

3. Proton is nucleus of deuterium

4. Proton is ionized hydrogen molecule

Q. Calculate the number of oxygen atoms in 0.10 mole of Na2 Co3 . 10H2O

Q.

An atom has mass number 23 and atomic number 11. What is the number of electrons in this atom?

Q.

Give reasons for the following statement.

$\mathrm{Helium}$ is a monoatomic molecule